I am seeing the thread and advising against sending anything from Portugal to Spain, or from France into Spain, through the national post office systems. The reason is simple. Despite the harmonization effects of the European Union, each country continues to maintain a national mail system that treats these intra-EU shipments as international shipments. So, instead of a point-to-point parcel delivery system like FedEx, UPS, DHL, etc., you have to deal with a veritable pipe organ...
This means, for example, that a parcel mailed from anywhere in Portugal will go to Lisbon first, then into their export scheme, then to Madrid, where the Spanish Correos will process this as an import item, despite the fact that there are no actual customs controls. It is just how the process is organized. From Madrid, the imported item goes into the Spanish distribution network.
This adds time, distance and complexity to your shipment. It also adds an element of uncertainty. In my case, a box mailed from Porto, travelling some 250 km to Santiago (figured direct), instead went to Lisbon, Madrid, Sevilla, and thence eventually on to Santiago... What should have taken 2-3 days maximum, took some 10 days.
The CTT (Portugal), El Correos (Spain) and La Post (France) all have apps that allow you to track your shipment using your smartphone. They all work great. In my experience from PT to ES, I watched in the apps as my parcel mailed to Ivar, went "higgly-piggily" all over Portugal and Spain. It eventually showed up at Ivar's some three days AFTER I flew home to the US, I retrieved my stuff on my next trip there.
If you are starting in Lisbon and planning to be on Camino for three to four weeks, this should be plenty of time for a parcel to get to Ivar, even considering my experience. So, from Lisbon, you should be okay. However, once you are on the way north, reconsider using the CTT, in favor of checking out UPS, DHL, or another parcel delivery service that operated outside the national postal systems.
Hope this helps.
